Absorbent article having a breathable backsheet

ABSTRACT

A disposable absorbent article having a breathable laminate backsheet. The absorbent article has a front waist region, a rear waist region, a crotch region positioned between the front waist region and the rear waist region, a pair of opposed side edges, a first end edge and a second end edge. The absorbent article includes an absorbent core having a pair of opposing longitudinal edges, a garment-facing side and a body-facing side, and a breathable laminate backsheet disposed adjacent to the garment-facing side of the absorbent core. The breathable laminate backsheet has an inner layer and an outer layer joined to one another. The inner layer is positioned between the absorbent core and the outer layer. The outer layer is relatively vapor pervious. The inner layer is substantially liquid impermeable and substantially vapor pervious. The inner layer is longitudinally coterminous with the absorbent article and of a smaller transverse width than the front waist region, the rear waist region, and the crotch region so as to form a breathable zone which is longitudinally coterminous with the absorbent article and adjacent to each of the side edges.

FIELD OF INVENTION

The present invention relates generally to disposable absorbent articlessuch as disposable diapers and, more particularly, to disposableabsorbent articles having a breathable laminate backsheet.

BACKGROUND OF THE INVENTION

Infants and other incontinent individuals wear disposable absorbentarticles such as diapers to receive and contain urine and other bodyexudates. Absorbent articles function both to contain the dischargedmaterials and to isolate these materials from the body of the wearer andfrom the wearer's garments and bed clothing. Disposable absorbentarticles having many different basic designs are known to the art. It isalso known that the exterior of disposable diapers can be covered with aflexible, liquid and vapor impervious sheet to prevent any absorbedliquid from passing through the diaper and soiling adjacent articlessuch as clothing, bedding and the like. These outer covers, generallyreferred to as backsheets, are often constructed from fluid imperviousfilms such as polyethylene. Although such backsheets do prevent liquidfrom passing through the diaper, they also can make the diaper feel hotand uncomfortable to wear because of their impermeability to air and/ormoisture.

Backsheets which are pervious to vapor are generally known as breathablebacksheets and have been described in the art. In general, thesebacksheets are intended to allow the passage of vapor through them whileretarding the passage of liquid. For example, U.S. Pat. No. 3,156,242issued to Crowe, Jr. on Nov. 10, 1964 teaches the use of a microporousfilm as a breathable backsheet. U.S. Pat. No. 3,881,489, issued toHartwell on May 6, 1975, teaches a breathable backsheet comprising incombination two layers, the first of which is a low void volumeperforated thermoplastic film and the second of which is a porous highvoid volume hydrophobic tissue. U.S. Pat. No. 3,989,867 issued to Sissonon Nov. 2, 1976 teaches a breathable backsheet provided with taperedhollowed bosses which prevent the passage of liquids while allowingvapors to pass readily therethrough.

While these backsheets do provide improvements over the impermeablebacksheets of the prior art, comfort, dryness, and vapor exchange(breathability) remains as key design considerations. Accordingly,devices providing for better retention and absorption of liquids whileproviding for the more efficient passage of vapor have been sought.

Therefore, it is an object of the present invention to provide adisposable absorbent article having a breathable backsheet to ensurecomfort for the wearer.

It is yet another object of this invention to provide a disposableabsorbent article having a backsheet comprising zones of breathability,wherein the backsheet further comprises a vapor pervious and/or liquidpervious nonwoven web which provides the garment-facing surface of thebacksheet with a cloth-like feel.

It is still another object of the present invention to provide adisposable absorbent article having good containment and breathabilitycharacteristics that is economical and easy to manufacture at highspeeds.

SUMMARY OF THE INVENTION

A disposable absorbent article having a front waist region having atransverse width, a rear waist region having a transverse width, acrotch region having a transverse width positioned between the frontwaist region and the rear waist region, a pair of opposed side edges, afirst end edge located in the front waist region and a second end edgelocated in the rear waist region. The absorbent article comprises anabsorbent core having a pair of opposing longitudinal edges, agarment-facing side and a body-facing side and a breathable laminatedisposed adjacent said garment-facing side of said absorbent core. Thebreathable laminate comprises an inner layer and an outer layer joinedto one another. The inner layer is positioned between the absorbent coreand the outer layer. The outer layer is relatively vapor pervious, andthe inner layer is substantially liquid impermeable and substantiallyvapor pervious. The inner layer is longitudinally coterminous with saidabsorbent article and of a smaller transverse width than the transversewidth of said front waist region, said rear waist region, and saidcrotch region so as to form a breathable zone which is longitudinallycoterminous with said absorbent article and adjacent to each of saidside edges.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as formingthe present invention, it is believed that the invention will be betterunderstood from the following description which is taken in conjunctionwith the accompanying drawings in which like designations are used todesignate substantially identical elements, and in which:

FIG. 1 is a plan view of a disposable diaper embodiment of the presentinvention having portions cut away to reveal underlying structure, theinner surface of the diaper is facing the viewer;

FIG. 2 is a plan view of a laminate backsheet suitable for use in thediaper of the present invention with the body-facing side of thebacksheet facing the viewer;

FIG. 3 is an enlarged, cross-sectional view of the laminate backsheet ofFIG. 2; and

FIG. 4 an enlarged, cross-sectional view of one embodiment of adisposable absorbent article comprising the backsheet shown in FIGS.2-3.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "absorbent article" refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain the various exudates discharged from thebody. The term "disposable" is used herein to describe absorbentarticles which are not intended to be laundered or otherwise restored orreused as an absorbent article (i.e., they are intended to be discardedafter a single use and, preferably, to be recycled, composted orotherwise disposed of in an environmentally compatible manner). A"unitary" absorbent article refers to absorbent articles which areformed of separate parts united together to form a coordinated entity sothat they do not require separate manipulative parts like a separateholder and liner. A preferred embodiment of an absorbent article of thepresent invention is the unitary disposable absorbent article, diaper20, shown in FIG. 1. As used herein, the term "diaper" refers to anabsorbent article generally worn by infants and incontinent persons thatis worn about the lower torso of the wearer. It should be understood,however, that the present invention is also applicable to otherabsorbent articles such as incontinence briefs, incontinenceundergarments, diaper holders and liners, feminine hygiene garments,training pants, and the like.

FIG. 1 is a plan view of the diaper 20 of the present invention in itsflat-out, uncontracted state (i.e., with elastic induced contractionpulled out) with portions of the structure being cut-away to moreclearly show the construction of the diaper 20 and with the portion ofthe diaper 20 which faces the wearer, the inner surface 40, facing theviewer. As shown in FIG. 1, the diaper 20 preferably comprises acontainment assembly 22 comprising a liquid pervious topsheet 24; alaminate backsheet 26 joined to the topsheet; and an absorbent core 28positioned between the topsheet 24 and the laminate backsheet 26. Theabsorbent core 28 has a pair of opposing longitudinal edges 60, abody-facing side 62 and a garment-facing side 64. The diaper preferablyfurther comprises side panels 30; elasticized leg cuffs 32; elasticizedwaistbands 34; and a fastening system 36 preferably comprising a pair ofsecurement members 37 and a landing member 38.

The diaper 20 is shown in FIG. 1 to have an inner surface 40 (facing theviewer in FIG. 1), an outer surface 42 opposed to the inner surface 40,a rear waist region 44, a front waist region 46 opposed to the rearwaist region 44, a crotch region 48 positioned between the rear waistregion 44 and the front waist region 46, and a periphery which isdefined by the outer perimeter or edges of the diaper 20 in which theside or longitudinal edges are designated 50 and the end edges aredesignated 52. The inner surface 40 of the diaper 20 comprises thatportion of the diaper 20 which is positioned adjacent to the wearer'sbody during use (i.e., the inner surface 40 generally is formed by atleast a portion of the topsheet 24 and other components joined to thetopsheet 24). The outer surface 42 comprises that portion of the diaper20 which is positioned away from the wearer's body (i.e., the outersurface 42 is generally formed by at least a portion of the laminatebacksheet 26 and other components joined to the laminate backsheet 26).As used herein, the term "joined" encompasses configurations whereby anelement is directly secured to the other element by affixing the elementdirectly to the other element, and configurations whereby the element isindirectly secured to the other element by affixing the element tointermediate member(s) which in turn are affixed to the other element.The rear waist region 44 and the front waist region 46 extend from theend edges 52 of the periphery to the crotch region 48.

The diaper 20 also has two centerlines, a longitudinal centerline 100and a transverse centerline 110. The term "longitudinal", as usedherein, refers to a line, axis, or direction in the plane of the diaper20 that is generally aligned with (e.g. approximately parallel with) avertical plane which bisects a standing wearer into left and righthalves when the diaper 20 is worn. The terms "transverse" and "lateral",as used herein, are interchangeable and refer to a line, axis ordirection which lies within the plane of the diaper that is generallyperpendicular to the longitudinal direction (which divides the wearerinto front and back body halves).

The containment assembly 22 of the diaper 20 is shown in FIG. 1 ascomprising the main body (chassis) of the diaper 20. The containmentassembly 22 preferably comprises a topsheet 24, a laminate backsheet 26and an absorbent core 28 having a pair of opposing longitudinal edges60, a body-facing side 62, and a garment-facing side 64. The body-facingside 62 generally faces the body of the wearer while the garment-facingside 64 generally faces away from the body of the wearer. When theabsorbent article comprises a separate holder and a liner, thecontainment assembly 22 generally comprises the holder and the liner(i.e., the containment assembly 22 comprises one or more layers ofmaterial to define the holder while the liner comprises an absorbentcomposite such as a topsheet, a laminate backsheet, and an absorbentcore.) For unitary absorbent articles, the containment assembly 22preferably comprises the topsheet 24, the backsheet 26 and the absorbentcore 28 of the diaper with other features added to form the compositediaper structure.

FIG. 1 shows a preferred embodiment of the containment assembly 22 inwhich the topsheet 24 and the laminate backsheet 26 have length andwidth dimensions generally larger than those of the absorbent core 28.The topsheet 24 and the laminate backsheet 26 extend beyond the edges ofthe absorbent core 28 to thereby form the periphery of the diaper 20.While the topsheet 24, the laminate backsheet 26, and the absorbent core28 may be assembled in a variety of well known configurations, exemplarycontainment assembly configurations are described generally in U.S. Pat.No. 3,860,003 entitled "Contractible Side Portions for DisposableDiaper" which issued to Kenneth B. Buell on Jan. 14, 1975; and U.S. Pat.No. 5,151,092 entitled "Absorbent Article With Dynamic Elastic WaistFeature Having A Predisposed Resilient Flexural Hinge" which issued toKenneth B. Buell et al., on Sep. 29, 1992; each of which is incorporatedherein by reference.

The absorbent core 28 may be any absorbent member which is generallycompressible, conformable, non-irritating to the wearer's skin, andcapable of absorbing and retaining liquids such as urine and othercertain body exudates. As shown in FIG. 1, the absorbent core 28 has agarment-facing side 64, a body-facing side 62, a pair of side edges 60,and a pair of waist edges. The absorbent core 28 may be manufactured ina wide variety of sizes and shapes (e.g., rectangular, hourglass,"T"-shaped, asymmetric, etc.) and from a wide variety ofliquid-absorbent materials commonly used in disposable diapers and otherabsorbent articles such as comminuted wood pulp which is generallyreferred to as airfelt. Examples of other suitable absorbent materialsinclude creped cellulose wadding; meltblown polymers including coform;chemically stiffened, modified or cross-linked cellulosic fibers; tissueincluding tissue wraps and tissue laminates; absorbent foams; absorbentsponges; superabsorbent polymers; absorbent gelling materials; or anyequivalent material or combinations of materials.

The configuration and construction of the absorbent core 28 may vary(e.g., the absorbent core may have varying caliper zones, a hydrophilicgradient, a superabsorbent gradient, or lower average density and loweraverage basis weight acquisition zones; or may comprise one or morelayers or structures). Further, the size and absorbent capacity of theabsorbent core 28 may also be varied to accommodate wearers ranging frominfants through adults. However, the total absorbent capacity of theabsorbent core 28 should be compatible with the design loading and theintended use of the diaper 20.

One embodiment of the diaper 20 has an asymmetric, modified T-shapedabsorbent core 28 having ears in the front waist region but a generallyrectangular shape in the rear waist region. Exemplary absorbentstructures for use as the absorbent core 28 of the present inventionthat have achieved wide acceptance and commercial success are describedin U.S. Pat. No. 4,610,678 entitled "High-Density Absorbent Structures"issued to Weisman et al. on Sep. 9, 1986; U.S. Pat. No. 4,673,402entitled "Absorbent Articles With Dual-Layered Cores" issued to Weismanet al. on Jun. 16, 1987; U.S. Pat. No. 4,888,231 entitled "AbsorbentCore Having A Dusting Layer" issued to Angstadt on Dec. 19, 1989; andU.S. Pat. No. 4,834,735, entitled "High Density Absorbent Members HavingLower Density and Lower Basis Weight Acquisition Zones", issued toAlemany et al. on May 30, 1989. The absorbent core may further comprisethe dual core system containing an acquisition/distribution core ofchemically stiffened fibers positioned over an absorbent storage core asdetailed in U.S. Pat. No. 5,234,423, entitled "Absorbent Article WithElastic Waist Feature and Enhanced Absorbency" issued to Alemany et al.,on Aug. 10, 1993; and in U.S. Pat. No. 5,147,345, entitled "HighEfficiency Absorbent Articles For Incontinence Management" issued toYoung, LaVon and Taylor on Sep. 15, 1992. All of these patents areincorporated herein by reference.

The topsheet 24 is preferably positioned adjacent the body-facing side62 of the absorbent core 28 and is preferably joined thereto and to thelaminate backsheet 26 by attachment means (not shown) such as those wellknown in the art. Suitable attachment means are described with respectto joining the laminate backsheet 26 to the absorbent core 28. In apreferred embodiment of the present invention, the topsheet 24 and thelaminate backsheet 26 are joined directly to each other in the diaperperiphery and are indirectly joined together by directly joining them tothe absorbent core 28 by any suitable attachment means.

The topsheet 24 is preferably compliant, soft feeling, andnon-irritating to the wearer's skin. Further, the topsheet 24 ispreferably liquid pervious permitting liquids (e.g., urine) to readilypenetrate through its thickness. A suitable topsheet 24 may bemanufactured from a wide range of materials such as woven and nonwovenmaterials; polymeric materials such as apertured formed thermoplasticfilms, apertured plastic films, and hydroformed thermoplastic films;porous foams; reticulated foams; reticulated thermoplastic films; andthermoplastic scrims. Suitable woven and nonwoven materials can becomprised of natural fibers (e.g., wood or cotton fibers), syntheticfibers (e.g., polymeric fibers such as polyester, polypropylene, orpolyethylene fibers) or from a combination of natural and syntheticfibers. The topsheet 24 is preferably made of a hydrophobic material toisolate the wearer's skin from liquids which have passed through thetopsheet 24 and are contained in the absorbent core 28 (i.e. to preventrewet). If the topsheet 24 is made of a hydrophobic material, at leastthe upper surface of the topsheet 24 is treated to be hydrophilic sothat liquids will transfer through the topsheet more rapidly. Thisdiminishes the likelihood that body exudates will flow off the topsheet24 rather than being drawn through the topsheet 24 and being absorbed bythe absorbent core 28. The topsheet 24 can be rendered hydrophilic bytreating it with a surfactant. Suitable methods for treating thetopsheet 24 with a surfactant include spraying the topsheet 24 materialwith the surfactant and immersing the material into the surfactant. Amore detailed discussion of such a treatment and hydrophilicity iscontained in U.S. Pat. No. 4,988,344 entitled "Absorbent Articles withMultiple Layer Absorbent Layers" issued to Reising, et al on Jan. 29,1991 and U.S. Pat. No. 4,988,345 entitled "Absorbent Articles with RapidAcquiring Absorbent Cores" issued to Reising on Jan. 29, 1991, each ofwhich is incorporated by reference herein.

An alternative preferred topsheet comprises an apertured formed film.Apertured formed films are preferred for the topsheet because they arepervious to body exudates and yet non-absorbent and have a reducedtendency to allow liquids to pass back through and rewet the wearer'sskin. Thus, the surface of the formed film which is in contact with thebody remains dry, thereby reducing body soiling and creating a morecomfortable feel for the wearer. Suitable formed films are described inU.S. Pat. No. 3,929,135, entitled "Absorptive Structures Having TaperedCapillaries", which issued to Thompson on Dec. 30, 1975; U.S. Pat. No.4,324,246 entitled "Disposable Absorbent Article Having A StainResistant Topsheet", which issued to Mullane, et al. on Apr. 13, 1982;U.S. Pat. No. 4,342,314 entitled "Resilient Plastic Web ExhibitingFiber-Like Properties", which issued to Radel. et al. on Aug. 3, 1982;U.S. Pat. No. 4,463,045 entitled "Macroscopically ExpandedThree-Dimensional Plastic Web Exhibiting Non-Glossy Visible Surface andCloth-Like Tactile Impression", which issued to Ahr et al. on Jul. 31,1984; and U.S. Pat. No. 5,006,394 "Multilayer Polymeric Film" issued toBaird on Apr. 9, 1991. Each of these patents are incorporated herein byreference.

The laminate backsheet 26 of the present invention is that portion ofthe diaper 20 which is generally positioned away from the wearer's skinand which prevents the exudates absorbed and contained in the absorbentcore 28 from wetting articles which contact the diaper 20 such asbedsheets and undergarments.

The laminate backsheet 26 is preferably positioned adjacent thegarment-facing side 64 of the absorbent core 28 and is preferably joinedthereto by any suitable attachment means known in the art. For example,the laminate backsheet 26 may be secured to the absorbent core 28 by auniform continuous layer of adhesive, a patterned layer of adhesive, oran array of separate lines, spirals, or spots of adhesive. Adhesiveswhich have been found to be satisfactory are manufactured by H. B.Fuller Company of St. Paul, Minn. and marketed as HL-1258. An example ofa suitable attachment means comprising an open pattern network offilaments of adhesive is disclosed in U.S. Pat. No. 4,573,986 entitled"Disposable Waste-Containment Garment", which issued to Minetola et al.on Mar. 4, 1986. Another suitable attachment means comprising severallines of adhesive filaments swirled into a spiral pattern is illustratedby the apparatus and methods shown in U.S. Pat. No. 3,911,173 issued toSprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996 issued to Ziecker,et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666 issued to Wereniczon Jun. 27, 1989. Each of these patents are incorporated herein byreference. Alternatively, the attachment means may comprise heat bonds,pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any othersuitable attachment means or combinations of these attachment means asare known in the art.

Embodiments of the present invention are also contemplated wherein theabsorbent core 28 is not joined to the laminate backsheet 26, and/or thetopsheet 24 in order to provide greater extensibility especially in thefront waist region 46 and the rear waist region 44.

The laminate backsheet 26 of the present invention, as shown in FIGS.2-3, comprises an inner layer 90 and an outer layer 92 joined to oneanother. The means by which the inner layer 90 and the outer layer 92are joined to one another include any means known in the art such asadhesives, heat, pressure, heat and pressure, extrusion, and ultrasonicbonds. The laminate backsheet 26 has a body-facing side 72, agarment-facing side 70, a central region 74 and two outer regions 76.Further, the laminate backsheet 26 comprises at least three distinctzones, a first breathable zone 82, and two opposing second breathablezones 80. The first breathable zone 82 preferably comprises the centralregion 74 of the laminate backsheet 26 and is juxtaposed at least aportion of the garment-facing side 64 of the absorbent core 28. Thefirst breathable zone 82 provides a substantially liquid impermeablestructure that contains the liquids that have passed into thecontainment assembly 22. In a preferred embodiment, the first breathablezone 82 covers the entire garment-facing side 64 of the absorbent core28. (As used herein, the term "covers" means that one member isgenerally, either directly or indirectly in a face-to-face relationshipwith another member.) In an especially preferred embodiment, the firstbreathable zone 82 not only covers the garment-facing side 64 of theabsorbent core 28, but also extends laterally outwardly to at least anylocation at which any barrier cuffs (described below) that may be joinedto the diaper 20, such as the proximal edge 33 of the barrier cuffs 32.(As used herein, the term "laterally outwardly" refers to a directionaway from the longitudinal centerline 100.) This insures that any liquidabsorbed by the absorbent core 28 or otherwise deposited into thecontainment assembly 22 of the diaper 20 will not seep through thesecond breathable zones 80 of the laminate backsheet 26.

The outer layer 92 preferably comprises a nonwoven web. However,embodiments are contemplated wherein the outer cover 92 comprisesmaterials such as woven webs, foams, scrims, films, or any othermaterial or combination of materials known in the art that would givethe diaper a clothlike look and/or feel and is at a minimum airpermeable. The outer layer 92 covers the entire laminate backsheet 26thereby forming the periphery of the diaper 20. In addition, thenonwoven web of the outer layer 92 provides the diaper with a cloth-likelook and feel. Further, the outer layer 92 may provide the diaper with alow cost landing zone capable of engaging hook and loop type fasteners.Such a landing zone could be utilized as a portion of a primaryfastening system or as a means for disposing of a soiled diaper.

The nonwoven web of the outer layer 92 is liquid and air pervious toallow free vapor passage in the second breathable zones 80. The nonwovenweb may comprise natural fibers (e.g., cotton or wood fibers), or maycomprise fibers of polyethylene, polypropylene, polyester, or anycombination of such fibers. Further, the nonwoven web may be carded,spun melt, meltblown, or air-through bonded or have any othercharacteristic or be manufactured in any manner known in the art.Preferably, the nonwoven web is comprised of sufficient thermoplasticmaterial to allow for thermal bonding of the nonwoven web to othercomponents of the diaper. An especially preferred nonwoven web is acarded nonwoven web made of 100% polypropylene fibers such as FPN 290manufactured by FiberWeb North America of Simpsonville, S.C. It may bedesirable, however, to provide an outer layer 92 that acts to change theperviousness (either vapor or liquid) in certain regions of the secondbreathable zones 80. Such may be the case in disposable article designswherein the second breathable zones 80 underlie or are otherwise incontact with any portion of the article which may absorb liquids. Insuch cases, it may be desirable to use a hydrophobic nonwoven web tohelp prevent any leakage of the liquids from the article.

Interposed between the absorbent core 28 and the outer layer 92 is innerlayer 90. The inner layer 90 prevents fluids retained by the absorbentcore 28 from striking through the diaper 20 and soiling adjacentgarments. Therefore, the inner layer 90 must be at least substantiallyfluid impervious and preferably, completely fluid impervious. Suitablematerials are well known in the art, include woven and nonwoven fabricswhich have been treated to render them liquid-repellent. Breathable orvapor pervious liquid resistant materials, and those materials describedin U.S. Pat. No. 3,881,489 issued to Hartwell on May 6, 1975 and U.S.Pat. No. 3,989,867 issued to Sisson on Nov. 2, 1976 can also be used.These patents are incorporated herein by reference.

The size of the inner layer 90 is a key factor in forming the firstbreathable zone 82 and the second breathable zones 80. The size andshape of the inner layer 90 generally determines the size, shape, andlocation of the first breathable zone 82 and the second breathable zones80. While the inner layer 90 is longitudinally coterminous with (i.e.,the same length as) the diaper 20, the inner layer 90 has a smallertransverse width than the transverse width of the diaper 20 in the frontwaist region 46, the rear waist region 44 and the crotch region 48 sothat a second breathable zone 80 is formed in the diaper 20 which islongitudinally coterminous with the diaper 20. Therefore, the innerlayer 90 may generally be of any shape and size that conforms to theabove description to permit the laminate backsheet 26 to have twoopposed second breathable zones 80 which are longitudinally coterminouswith the diaper 20.

While the inner layer 90 is longitudinally coterminous with the outerlayer 92, the inner layer 90 has a smaller transverse width than that ofthe outer layer 92 in all regions of the diaper, i.e., the front waistregion 46, the rear waist region 44, and the crotch region 48 so that asecond breathable zone 80 is formed in the backsheet 26 which islongitudinally coterminous with the backsheet 26.

A preferred shape of the inner layer 90 is shown in FIG. 2. The innerlayer 90 has a uniform transverse width. In addition, the inner layerhas a uniform transverse width which is smaller than the narrowestportion of the crotch region 48 of the diaper 20. With thisconfiguration two opposed second breathable zones 80 are formed whichare longitudinally coterminous with the diaper 20.

For disposable absorbent articles, and particularly for garments such asdiapers which are form-fitting such as those disclosed herein, thebreathability exhibited by the backsheet has been found critical to theperformance of the absorbent article especially in hot and humidconditions. When an absorbent article is positioned on a wearer, theskin is occluded by the materials making up the absorbent article. Thisocclusion of the skin, especially in hot and humid conditions, preventsevaporation and resulting cooling of the occluded area. The resultantperspiration raises the relative humidity of air inside of the absorbentarticle resulting in less comfort for the wearer and perceived negativebenefits by caregivers. In addition, incidents of heat rash and othernegative skin macerations can increase if the absorbent article does nothave sufficient capability to move the water vapor created by the bodyout of the absorbent article.

Conventional diapers have attempted to use breathable materials toreduce the humidity within the diaper. However, these materials have notprovided sufficient moisture vapor transmission rates to reduce thehumidity inside the product to an extent that provides the wearercomfort when exposed to hot and humid conditions.

It has been found that the moisture vapor transmission rate of theopposing second breathable zones 80 of the backsheet 26 in conjunctionwith the overall vapor transmission rate of the rest of the backsheet isimportant in reducing the incidents of heat rash and other skin problemsassociated with high heat and humidity conditions. In order to reducehumidity and heat build up within the absorbent article, it has beenfound that the second breathable zones 80 of the backsheet 26 shouldhave a mass vapor transmission rate of at least about 2500 g/m² /24 hr.,more preferably at least about 3000 g/m² /24 hr.

The central region 74 which comprises the first breathable zone 82 issubstantially liquid impermeable to contain liquids absorbed by theabsorbent core 28. Since the central region 74 comprising the firstbreathable zone 82 must contain liquids absorbed by the absorbent coreit typically has a lower mass vapor transmission rate than the secondbreathable zones 80 which are not relied upon to contain any of theabsorbed liquids. Accordingly, it has been found that the firstbreathable zone 82 is the main limiting factor in providing an overallabsorbent article with a high average mass vapor transmission rate.However, it has been found that the first breathable zone 82 should havea mass vapor transmission rate of at least about 1500 g/m² /24 hr., morepreferably at least about 2000 g/m² /24 hr. The first breathable zone 82and thus the entire absorbent article, given the materials, wouldgenerally have a mass vapor transmission rate in a range at least fromabout 1500 g/m² /24 hr. to about 8000 g/m² /24 hr., more preferably fromabout 2000 g/m² /24 hr. to about 7000 g/m² /24 hr. Thus, it is preferredthat each zone of the backsheet 26 should have a mass vapor transmissionrate of at least about 1500 g/m² /24 hr. As can be seen, because thefirst breathable zone 82 comprises both the inner layer 90 and the outerlayer 92, it has an effective mass vapor transmission rate which is lessthan that of the second breathable zones 80 which comprise only theouter layer 92. This is expected as the first breathable zone 82 isresponsible for retaining liquids absorbed by the absorbent core 28 frompassing through the laminate backsheet 26 while the second breathablezones 80 of the laminate backsheet 26 do not need to assist in thecontainment of liquids within the disposable diaper 20.

The moisture vapor transmission rate is measured by the method set forthbelow. A known amount of CaCl₂ is put into a flanged cup. A sample isplaced on the top of the cup and held securely by a retaining ring andgasket. The assembly is then weighed and recorded as the initial weight.The assembly is placed in a constant temperature (40° C.) and humidity(75% RH) chamber for 5 hours. The assembly is then removed from thechamber and allowed to equilibrate for at least 30 minutes at thetemperature of the room where the balance is located. The assembly isthen weighed and recorded as the final weight. The mass vaportransmission rate (MVTR) is calculated and expressed in g/m² /24 hr.using the following formula: ##EQU1##

In embodiments of the present invention comprising leg cuffs 32, asdescribed below, the second breathable zones 80 may be disposedlaterally inwardly or outwardly of the leg cuffs 32. Further, the secondbreathable zones 80 may form a portion of the leg cuffs 32. However, ina preferred embodiment, the second breathable zones 80 extend laterallyoutwardly from the proximal edge 33 of the leg cuffs 32. In anotherpreferred embodiment of the present invention, the second breathablezones 80 extend laterally outwardly from a location that is laterallyoutboard of the proximal edge 33 of the leg cuff 32 and laterallyinboard of the gasketing cuff 63. Such a configuration provides thediaper 20 with a liquid impervious gasketing seal about the legs of thewearer that prevents liquids from escaping the containment assembly 22of the diaper 20. In yet another embodiment, the second breathable zones80 extend laterally outwardly from a location laterally outboard of thegasketing cuff 63.

It may also be desirable to provide the disposable article of thepresent invention with extensibility or elasticity in all or a portionof the side panels 30. (As used herein, the term "extensible" refers tomaterials that are capable of extending in at least one direction to acertain degree without undue rupture. The terms "elasticity" and"elastically extensible" refer to extensible materials that have theability to return to approximately their original dimensions after theforce that extended the material is removed. As used herein, anymaterial or element described as "extensible" may also be elasticallyextensible unless otherwise provided.) Extensible side panels 30 providea more comfortable and contouring fit by initially conformably fittingthe diaper to the wearer and sustaining this fit throughout the time ofwear well passed when the diaper has been loaded with exudates since theside panels allow the sides of the diaper to expand and contract.Extensible side panels 30 further provide more effective application ofthe diaper 20 since even if the diaperer pulls one side panel 30 fartherthan the other during the application (asymmetrically), the diaper 20will "self-adjust" during wear. While the extensible side panels 30 maybe constructed in a number of configurations, examples of diapers withextensible side panels are disclosed in U.S. Pat. No. 4,857,067,entitled "Disposable Diaper Having Shirred Ears" issued to Wood, et al.on Aug. 15, 1989; U.S. Pat. No. 4,381,781 issued to Sciaraffa, et al. onMay 3, 1983; U.S. Pat. No. 4,938,753 issued to Van Gompel, et al. onJul. 3, 1990; and in U.S. Pat. No. 5,151,092 issued to Buell et al. onSep. 29, 1992; each of which are incorporated herein by reference.

The extensible side panels 30, or any other elements of the diaper 20 inwhich extensibility or elasticity is desirable such as the waistbands 34may comprise materials that have been "prestrained", or "mechanicallyprestrained" (i.e., subjected to some degree of localized patternmechanical stretching to permanently elongate the material), orstructure elastic-like webs (SELF), as described below. The materialsmay be prestrained using deep embossing techniques as are known in theart. Alternatively, the materials may be prestrained by directing thematerial through an incremental mechanical stretching system asdescribed in U.S. Pat. No. 5,330,458 entitled "Absorbent Article WithElastic Feature Having A Portion Mechanically Prestrained" issued toBuell et al., on Jul. 19, 1994. The materials are then allowed to returnto their substantially untensioned condition, thus forming a zero strainstretch material that is extensible, at least up to the point of initialstretching. Examples of zero strain materials are disclosed in U.S. Pat.No. 2,075,189 issued to Galligan on Mar. 30, 1937; U.S. Pat. No.3,025,199 issued to Harwood on Mar. 13, 1962; U.S. Pat. Nos. 4,107,364and 4,209,563 issued to Sisson on Aug. 15, 1978 and Jun. 24, 1980,respectively; U.S. Pat. No. 4,834,741 issued to Sabee on May 30, 1989;and U.S. Pat. No. 5,151,092 issued to Buell et al., on Sep. 29, 1992.All of the above referenced patents are hereby incorporated byreference.

Alternatively, the extensible side panels 30 or any portions of the sidepanels 30 or the materials included in the side panels or any otherelement of the diaper 20 in which extensibility is desirable maycomprise a structural elastic-like film (SELF) web. A structuralelastic-like film web is an extensible material that exhibits anelastic-like behavior in the direction of elongation without the use ofadded elastic materials. The SELF web includes a strainable networkhaving at least two contiguous, distinct, and dissimilar regions. One ofthe regions is configured so that it will exhibit resistive forces inresponse to an applied axial elongation in a direction parallel to thepredetermined axis before a substantial portion of the other regiondevelops significant resistive forces to the applied elongation. Atleast one of the regions has a surface-pathlength which is greater thanthat of the other region as measured substantially parallel to thepredetermined axis while the material is in an untensioned condition.The region exhibiting the longer surface-pathlength includes one or moredeformations which extend beyond the plane of the other region. The SELFweb exhibits at least two significantly different stages on controlledresistive force to elongation along at least one predetermined axis whensubjected to an applied elongation in a direction parallel to thepredetermined axis. The SELF web exhibits first resistive forces to theapplied elongation until the elongation of the web is sufficient tocause a substantial portion of the region having the longersurface-pathlength to enter the plane of applied elongation, whereuponthe SELF web exhibits second resistive forces to further elongation. Thetotal resistive forces to elongation are higher than the first resistiveforces to elongation provided by the first region. SELF webs suitablefor the present invention and the method for making such webs are morecompletely described in commonly assigned U.S. Pat. No. 5,518,801entitled "Web Materials Exhibiting Elastic-Like Behavior", issued toChappell, et al. on May 21, 1996, which is incorporated herein byreference.

The diaper 20 preferably further comprises elasticized leg cuffs 32 forproviding improved containment of liquids and other body exudates. Eachelasticized leg cuff 32 may comprise several different embodiments forreducing the leakage of body exudates in the leg regions. (The leg cuffcan be and is sometimes also referred to as leg bands, side flaps,barrier cuffs, or elastic cuffs.) U.S. Pat. No. 3,860,003 describes adisposable diaper which provides a contractible leg opening having aside flap and one or more elastic members to provide an elasticized legcuff (gasketing cuff). U.S. Pat. No. 4,909,803 entitled "DisposableAbsorbent Article Having Elasticized Flaps" issued to Aziz et al. onMar. 20, 1990, describes a disposable diaper having "stand-up"elasticized flaps (barrier cuffs) to improve the containment of the legregions. U.S. Pat. No. 4,695,278 entitled "Absorbent Article Having DualCuffs" issued to Lawson on Sep. 22, 1987; and U.S. Pat. No. 4,795,454entitled "Absorbent Article Having Leakage-Resistant Dual Cuffs" issuedto Dragoo on Jan. 3, 1989, describe disposable diapers having dual cuffsincluding a gasketing cuff and a barrier cuff. U.S. Pat. No. 4,704,115entitled "Disposable Waist Containment Garment" issued to Buell on Nov.3, 1987, discloses a disposable diaper or incontinence garment havingside-edge-leakage-guard gutters configured to contain free liquidswithin the garment. (Each of these patents are incorporated herein byreference.)

While each elasticized leg cuff 32 may be configured so as to be similarto any of the leg bands, side flaps, barrier cuffs, or elastic cuffsdescribed above, it is preferred that each elasticized leg cuff 32comprise at least an inner barrier cuff comprising a barrier flap and aspacing element such as described in the above-referenced U.S. Pat. No.4,909,803. In a preferred embodiment, the elasticized leg cuff 32additionally comprises an elastic gasketing cuff 63 with one or moreelastic strands 65, positioned outboard of the barrier cuff such asdescribed in the above-referred U.S. Pat. No. 4,695,278. Further, asshown in FIG. 4, the elasticized leg cuff 32 preferably has a proximaledge 33 and a distal edge 35. The distal edge 35 of the elasticized legcuff 32 is that part of the elasticized leg cuff 32 which is spaced awayfrom the chassis 22 of the diaper when the diaper 20 is being worn. Theproximal edge 33 is that part of the elasticized leg cuff 32 which isjoined to the chassis 22 of the diaper 20. The proximal edge 33 isgenerally located laterally inboard of the periphery of the diaper 20. Aportion of the elasticized leg cuff 32, however, may extend laterallyoutwardly from the proximal edge 33 such that the material covers atleast a portion of the outer region 76 of the backsheet 26. (not shown).An example of an elasticized cuff 32 having a portion extendinglaterally outwardly over most or all of the outer region 76 of thebacksheet 26 is described in the above-referenced U.S. Pat. No.4,795,454 issued to Dragoo, which is hereby incorporated by referenceherein.

The diaper 20 preferably further comprises an elasticized waistband 34that provides improved fit and containment. The elasticized waistband 34is that portion or zone of the diaper 20 which is intended toelastically expand and contract to dynamically fit the wearer's waist.The elasticized waistband 34 preferably extends longitudinally outwardlyfrom at least one of the waist edges of the absorbent core 28 andgenerally forms at least a portion of the end edge of the diaper 20.Disposable diapers are generally constructed so as to have twoelasticized waistbands, one positioned in the rear waist region and onepositioned in the front waist region, although diapers can beconstructed with a single elasticized waistband. Further, while theelasticized waistband 34 or any of its constituent elements can comprisea separate element affixed to the diaper 20, the elasticized waistband34 may be constructed as an extension of other elements of the diapersuch as the backsheet 26 or the topsheet 24, preferably both thebacksheet 26 and the topsheet 24. The elasticized waistband 34 may beconstructed in a number of different configurations including thosedescribed in U.S. Pat. No. 4,515,595 entitled "Disposable Diapers withElastically Contractible Waistbands" issued to Kievit et al. on May 7,1985 and the above referenced U.S. Pat. No. 5,151,092 issued to Buell;each of these references being incorporated herein by reference.

The diaper 20 also comprises a fastening system 36 which forms a sideclosure which maintains the rear waist region 44 and the front waistregion 46 in an overlapping configuration such that lateral tensions aremaintained around the circumference of the diaper to maintain the diaperon the wearer. Exemplary fastening systems are disclosed in U.S. Pat.No. 3,848,594 issued to Buell on Nov. 19, 1974; U.S. Pat. No. 4,662,875issued to Hirotsu and Robertson on May 5, 1987; U.S. Pat. No. 4,869,724issued to Scripps on Sep. 26, 1989; U.S. Pat. No. 4,846,815 issued toScripps on Jul. 11, 1989; U.S. Pat. No. 4,894,060 issued to Nestegard onJan. 16, 1990; U.S. Pat. No. 4,946,527 issued to Battrell on Aug. 7,1990; and U.S. Pat. No. 5,326,612 entitled "Nonwoven Female ComponentFor Refastenable Fastening Device And Method of Making the Same" issuedto David J. K. Goulait on Jul. 5, 1994. Each of these patents areincorporated herein by reference.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A disposable absorbent article having a frontwaist region having a transverse width, a rear waist region having atransverse width, a crotch region having a transverse width positionedbetween the front waist region and the rear waist region, a pair ofopposed side edges, a first end edge located in said front waist regionand a second end edge located in said rear waist region, said absorbentarticle comprising:an absorbent core having a pair of opposinglongitudinal edges, a garment-facing side and a body-facing side; and abreathable laminate disposed adjacent said garment-facing side of saidabsorbent core, said breathable laminate comprising an inner layer andan outer layer joined to one another, said inner layer being positionedbetween said absorbent core and said outer layer, said outer layer beingrelatively vapor pervious, said inner layer being substantially liquidimpermeable and substantially vapor pervious, said inner layer beinglongitudinally coterminous with said absorbent article and of a smallertransverse width than the transverse width of said front waist region,said rear waist region, and said crotch region so as to form abreathable zone which is longitudinally coterminous with said absorbentarticle and adjacent to each of said side edges.